Responses of leaf carbon, nitrogen, and phosphorus stoichiometry of Carex muliensis to water table drawdown in an alpine marsh on the Ruoergai Plateau, China.

Based on a field water table drawdown manipulation platform of Naleqiao marsh on the Rueorgai Plateau, we lifted in situ soil block of 1 m×1 m by 20 cm for simulating water table decline, and analyzed the response of carbon, nitrogen, and phosphorus stoichiometry in the wetland species Carex muliensis from June to September 2020. The results showed that there was no significant difference in leaf C content during the whole growing season, while N and P content gra-dually decreased along the growing season. After the drawdown of water table, the C content in leaves during the growing season was not consistent. Water table drawdown increased leaf C content in the early and middle growth stages, but changed little in the peak growth stage. Water table drawdown significantly increased leaf N content, while significantly decreased leaf P content. C:N, C:P, and N:P for leaves all increased along the whole growing period. The relative growth rate of C. muliensis was positively correlated with leaf C:N, but negatively correlated with leaf C:P and N:P. Water table drawdown significantly decreased leaf C:N, while significantly increased leaf C:P and N:P, which significantly reduced the relative growth rate of C. muliensis. The decrease of foliar P content induced by water table drawdown was the main regulating factor for the decrease of single leaf weight and specific leaf weight.

A chromosome-scale reference genome of Aquilegia oxysepala var. kansuensis.

The genus Aquilegia (Ranunculaceae) has been cultivated as ornamental and medicinal plants for centuries. With petal spurs of strikingly diverse size and shape, Aquilegia has also been recognized as an excellent system for evolutionary studies. Pollinator-mediated selection for longer spurs is believed to have shaped the evolution of this genus, especially the North American taxa. Recently, however, an opposite evolutionary trend was reported in an Asian lineage, where multiple origins of mini- or even nonspurred morphs have occurred. Interesting as it is, the lack of genomic resources has limited our ability to decipher the molecular and evolutionary mechanisms underlying spur reduction in this special lineage. Using long-read sequencing (PacBio Sequel), in combination with optical maps (BioNano DLS) and Hi-C, we assembled a high-quality reference genome of A. oxysepala var. kansuensis, a sister species to the nonspurred taxon. The final assembly is approximately 293.2 Mb, 94.6% (277.4 Mb) of which has been anchored to 7 pseudochromosomes. A total of 25,571 protein-coding genes were predicted, with 97.2% being functionally annotated. When comparing this genome with that of A. coerulea, we detected a large rearrangement between Chr1 and Chr4, which might have caused the Chr4 of A. oxysepala var. kansuensis to partly deviate from the "decaying" path that was taken before the split of Aquilegia and Semiaquilegia. This high-quality reference genome is fundamental to further investigations on the development and evolution of petal spurs and provides a strong foundation for the breeding of new horticultural Aquilegia cultivars.

Flavonols and Carotenoids in Yellow Petals of Rose Cultivar ( Rosa 'Sun City'): A Possible Rich Source of Bioactive Compounds.

Rose flowers have received increasing interest as rich sources of bioactive compounds. The composition of flavonols and carotenoids in yellow petals of Rosa 'Sun City' was determined by high-performance liquid chromatography coupled with photodiode array and mass spectrometric detectors (HPLC-PDA-MS). In total, 19 flavonols and 16 carotenoids were identified, some of which were first discovered in rose petals. Significant changes were observed in their profiles during seven blooming stages. Total flavonol contents showed the highest levels at stage 2 (S2; 1152.29 µg/g, FW). Kaempferol 7- O-glucoside and kaempferol 3- O-rhamnoside were the predominant individual flavonols. Total carotenoid concentration was highest at S4 (142.71 µg/g, FW). Violaxanthins with different geometrical configurations appeared as the major carotenoids across all blooming stages. These results indicated that 'Sun City' petals are rich sources of flavonols and carotenoids. Moreover, it is important to choose the appropriate harvest time on the basis of the targeted compounds.

Influence of environment and substrate quality on the decomposition of wetland plant root in the Sanjiang Plain, Northeast China.

The litterbag method was used to study the decomposition of wetland plant root in three wetlands along a water level gradient in the Sanjiang Plain, Northeast China. These wetlands are Calamagrostis angustifolia (C.aa), Carex meyeriana (C.ma) and Carex lasiocarpa (C.la). The objective of our study is to evaluate the influence of environment and substrate quality on decomposition rates in the three wetlands. Calico material was used as a standard substrate to evaluate environmental influences. Roots native to each wetland were used to evaluate decomposition dynamics and substrate quality influences. Calico mass loss was statistically different among the three wetlands in the upper soil profile (0-10 cm) and in the lower depth range (10-20 cm). Hydrology, temperature and pH all influence calico decomposition rates in different ways at different depths of the soil profiles. The decomposition rates of native roots declined differentially with the increase of depth in the soil profiles. The mass loss of native roots showed a statistical decrease among the three wetlands in the upper soil profile (0-10 cm) and in the lower depth range (10-20 cm) as C.ma wetland > C.aa wetland > C.la wetland. Both the C:P ratio and N:P ratio were positively interrelated with decomposition rates. Decomposition rates were negatively related to initial P concentration in all three wetlands, indicating that P concentration seems to be an important factor controlling the litter loss.